ON THE USE OF NEXRAD STAGE IV DATA
IN THE MULTIMEDIA MODELING OF POLLUTANT TRANSPORT
Brian K. Eder**, Sharon K. LeDuc", Alice B, Gilliland*. Peter L. Finkelstein*
Air Resources Laboratory
National Oceanic and Atmospheric Administration
Research Triangle Park, NC 27711
1. INTRODUCTION
The Environmental Protection Agency (EPA) is
designing the Multimedia Integrated Modeling System
(MIMS) to model the cycling of pollutants and nutrients
between the atmosphere and the earth's surface,
including water bodies and groundwater. Our ability to
accurately model both atmospheric, hydrological and
surface processes that transport chemicals is highly
dependent on precipitation types, rates and totals. Of
special interest are precipitation extremes and
subsequent flooding, which can greatly enhance the
movement of such chemicals. During such events, these
chemicals can enter the surface water bodies via
groundwater recharge as well as overland flow. For
example, the extreme flooding associated with Hurricane
Floyd, which made landfall in North Carolina during
September of 1999, transported tremendous amounts of
agricultural and industrial waste and pesticides into area
estuaries and rivers. This hurricane, which made landfall
shortly after an earlier hurricane, Dennis, inundated
sections of eastern North Carolina with more than 20
inches of rain.
During the development of MIMS, we are
investigating the use of the National Weather Service
NEXRAD (NEXt generation RADar) Stage IV precipitation
estimates in our modeling efforts. The NEXRAD Stage
IV data consist of precipitation data fields that have
assimilated both raingage data and WSR-88D (Weather
Surveillance Radar 1988 Doppler Version) data into a
comprehensive hourly, national dataset with a 4-km2
resolution.
The purpose of this research is to evaluate the
quality and identify limitations of the NEXRAD data
through a comparison with "ground truth" data obtained
from a network of ten closely space raingages. The
evaluation, which will use visualization tools and statistical
analyses will determine if the spatial resolution of
NEXRAD data is adequate to capture the spatial
variability of precipitation on the watershed that is used in
the surface hydrology models associated with MIMS.
* On assignment to the National Exposure Research
Laboratory, U. S. Environmental Protection Agency,
RTP.NC 27711
* Corresponding author address: Brian K. Eder, MD-80,
AMD, NERL, RTP, NC 27711; email: eder@hpcc.epa.gov
2. MIMS
The MIMS project was initiated by EPA's Office
of Research and Development to create a problem solving
software framework to support various ecosystem
modeling and environmental health assessment
(Johnston et al., 2000). The integration of environmental
models will introduce many challenges such as
atmospheric-terrestrial interactions, spatial and temporal
scale discrepancies, non-continuous grid structuring, and
database handling.
A comprehensive ecosystem exposure
assessment case study is being developed and tested in
the Neuse River basin in eastern North Carolina. This
river basin has drawn national attention because of its fish
kills and the discovery of the toxic dinoflagellate -
pfiesteria. The case study, which will measure aquatic
ecosystem health with fish health and water quality as the
initial endpoints, will provide a prototype focal point for
the MIMS software framework development.
3. NEXRAD STAGE IV DATA
The National Centers for Environmental
Prediction (NCEP), in cooperation with the Office of
Hydrology (OH), have developed the multi-sensor
National Precipitation Analysis (NPA). This analysis uses
approximately 3000 automated raingage observations in
conjunction with hourly digital precipitation radar
estimates obtained from the WSR-88D Radar Product
Generator. The data, which are available hourly and in
near real time, are gridded on a 131 x 131 4-km polar
stereographic grid centered over each of the nearly 100
radar sites in the contiguous United States. The
individual radar estimates are merged together on the
national Hydrologic Rainfall Analysis Project (HRAP). The
NPA uses the raingage data and an adjustment algorithm
developed by Smith and Krajewski (1991) to adjust the
radar data for biases. Once adjusted, the data are
adapted by NCEP to a national 4-km grid from algorithms
developed by OH. Data from grids which contain more
than one radar estimate are averaged together using an
inverse-distance weighted average. Currently, there is no
quality control of the estimates (e.g., removal of
anomalous propagation). The purpose of this study is to
assess the quality of these estimates and to determine if
they are suitable for use as input into the surface
hydrology models within the MIMS system.
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4. LIZZIE SITE CASE STUDY
The purpose of the Lizzie Research Station,
established by the North Carolina Department of Natural
Resources (NCDENR) in 1993, is to study groundwater
recharge and near-surface flow, The site covers 300+
acres of the drainage area of the Contentnea Creek,
which is within the Neuse River basin located in the
eastern part of the State. Approximately 50 groundwater
wells and 3 stream gages are maintained at the site. In
addition to the base network, water quality sampling has
now been added to the site as part of the MIMS project.
The water quality samples are collected from 18 of the 50
wells and one of the stream gages. These data will be
used to test watershed and groundwater models for
MIMS.
A total of 10 closely spaced raingages will be
located in a small stream system within the Neuse River
Basin. The locations of the raingage sites were selected
to provide coverage around two small tributaries, the
Middle Swamp and Sandy Run and to be juxtaposed to
the Lizzie Research Station. These 10 raingages will test
the validity of the NEXRAD Stage IV data for use in this
MIMS prototype case study and provide "ground truth"
precipitation values.
5. SUMMARY
Precipitation events, especially extreme events,
can greatly enhance overland flow and groundwater
recharge, thereby influencing the transport of pollutants
and nutrients. Accurate representation of precipitation
input into hydrology models is therefore critical. The
purpose of this research is to determine if NEXRAD data
can be used as input into hydrological models as part of
a MIMS prototype study taking place in the Neuse River
Basin of eastern North Carolina.
6. REFERENCES
Johnston, J.M. , J.H. Novak, and S.R. Kraemer, 2000:
Multimedia integrated modeling for
environmental protection: Introduction to a
collaborative framework. Environ. Monitor, and
Assess., 63, 253-263.
Smith, J. A., and W.F. Krajewski, 1991: Estimation of
mean field bias of radar rainfall estimates. J.
Appl. Meteor., 30, 397-412.
Disclaimer. This document has been reviewed and
approved by the U.S. Environmental Protection Agency
for publication. Mention of trade names or commercial
products does not constitute endorsement or
recommendation for use.
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NERL-RTP-AMD-00-220
TECHNICAL REPORT DATA
i. REPORT
3.RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
5.REPORT DATE
On The Use Of NEXRAD Stage IV Data In The Multimedia Modeling of
Pollutant Transport
6.PERFORMING ORGANIZATION CODE
7, AUTHOR(S)
Brian Eder, Sharon LeDuc, Alice Giliiland and Peter Finkelstein
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Same as Block 12
10.PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAHE AND ADDRESS
National Exposure Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
13.TYPE OF REPORT AND PERIOD COVERED
Conference Reprint
14. SPONSORING AGENCY CODE
EPA/600/9
15. SUPPLEMENTARY NOTES
16. ABSTRACT
The Environmental Protection Agency (EPA) is designing the Multimedia Integrated Modeling System (MIMS) to model (he
cycling of pollutants and nutrients between the atmosphere and the earth's surface, including water bodies and ground water. Our ability to
accurately model both atmospheric, hydrological and surface processes that transport chemicals is highly dependent on precipitation types.
rates and totals. Of special interest are precipitation extremes and subsequent Hooding, which can greatly enhance the movement of such
chemicals. During such events, these chemicals can enter the surface water bodies via groundwater recharge as well as overland flow. For
example, the extreme Hooding associated with Hurricane Floyd, which made landfall in North Carolina during September of IW9,
transported tremendous amounts of agricultural and industrial waste and pesticides into area estuaries and rivers. This hurricane, which'
made landfall shortly after an earlier hurricane. Dennis, inundated sections of eastern North Carolina with more than 20 inches of rain.
Duihig the development of MIMS, we are investigating the use of the National Weather Service NF.XRAD (NEXt generation KADar)
Stage IV precipitation estimates in our modeling efforts. The NEXRAD Stage IV data consist of precipitation data fields that have
assimilated both raingage data and WSR-88D (Weather Surveillance Radar 1988 Doppier Version) data into a comprehensive hourly.
national dataset with a 4-kmJ_resolution. The purpose of this research is to evaluate the quality and identify limitations of the NKXRAD
data through a comparison with "ground truth" data obtained from a network often closely space raingages. The evaluation, which will
use visualization tools and statistical analyses will determine if the spatial resolution of NEXRAD data is adequate to capture the spalial
variability of precipitation on the watershed that is used in the surface hydrology models associated with MIMS.
17. KEY WORDS AND DOCUMENT ANALYSIS
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